Modular multilevel battery (M2B) for electric vehicles

Abstract

Electromobility is expected to successfully compete with conventional propulsion technology in the near future and thus creates new challenges for the automotive industry. Major issues with state of the art electric vehicles (EVs) include limited range due to insufficient energy density and heavy weight of existing battery storage systems, unsatisfactory charging duration as well as comparatively high costs. A leap in power electronics technology might meet these challenges, as the aforementioned characteristics are predominantly determined by existing EV system architectures and power converters. This paper presents a novel modular multilevel parallel converter-based split battery system for electric vehicles, enabling dynamic switching of battery cells in parallel and in series. Each individual battery cell may be interconnected to its neighbours according to operational needs, e.g. to provide optimum source resistance, lowest state-of-charge (SOC) cycling, and balanced aging, rendering separate battery management systems (BMS) unnecessary. Applying the proposed technology in EVs may fundamentally change existing powertrain architectures and charger topologies, as it merges the battery storage system and the power converter. This forms the basis for a highly integrated power electronics unit that includes traction converter, battery charger, and BMS.